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yellomurci

A/C not working, calling JeffLambo

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So my a/c decided to stop blowing cold air today and before I take it in I thought I would check a few things.

When I turn it off and on from the eco button I cant hear the compressor clutch engage or disengage so I did a search on here and found a 2 year old thread where JeffLambo said the check the clutch fuse and in that situation it turned out to be correct.

The op said the fuse was behind the drivers seat with the clutch relay, anyone care to point me in the correct direction as I thought all the fuses etc were either in the passenger foot well or on the end of the dash?

Thanks for any help

The car is an 08 LP640 .

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Good to check the easy things first. Hope it’s something simple like a fuse for you.

For me, it was a slow refrigerant leak. Once the refrigerant gets below a certain level, a pressure switch in the drier cuts off the ac compressor.

I ended up replacing the compressor and drier because I could not find the leak even with dye.

So far so good. It was leaking out in about a month and it’s been 2 1/2 months since I did the work.

 

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I think he had already checked refrigerant level. If it's been a long time since you had the system charge it may be low. This is the normal issue.

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46 minutes ago, jefflambo said:

I think he had already checked refrigerant level. If it's been a long time since you had the system charge it may be low. This is the normal issue.

Thanks, I am going to get that checked first as you say but just covering my rear incase.

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The panel behind the driver seat will need to be removed to check these fuses if you are wanting to take a look, always good to eliminate possible issues before letting the dealers hand you a bill for doing the very same thing you can do yourself.

there are several areas that can cause this issue also, but take a look at the fuse block first, there is a good chance your system needs topped up though.

8AACE6D5-B8EC-4816-9280-35E653A26B7E.jpeg

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3 hours ago, yellomurci said:

Thanks, I am going to get that checked first as you say but just covering my rear incase.

If you want to check the amount of refrigerant the correct way, take it to any good mechanic that has an a/c machine that will pull out the refrigerant and weigh it as it comes out. My 04 takes about 2lbs of R134a. When I had a leak, the AC stopped working around 1.2 lbs. The LP640 is a very similar system.

Don't just have someone add refrigerant. That's a terrible practice that is perpetuated by the cans of DIY refrigerant in the parts stores. Modern a/c's suffer damage by adding too much refrigerant.

The only way to know you have the right amount of refrigerant is to remove it all and refill by weight. The machine should work and look something like this:

If you take out the refrigerant and weigh it, you will be able to know what is going on. Then you can fill it to the correct amount, and if it stops working again after a certain amount of time, you will know you have a leak and how bad that leak is.

Fun fact: If your mechanic doesn't have one of those machines and just adds refrigerant and uses gauges to check if your a/c system is filled with the right amount of refrigerant, then you know without a doubt that your mechanic is a hack and doesn't do things right with modern a/c systems.

A/C systems that are working as designed do not lose any refrigerant. So if your refrigerant is low, you have a leak, plain and simple. Finding and fixing the leaks isn't always plain and simple though.

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Oh, if you find you have a leak, I would start by changing the Schrader valves on the high and low side. They can be changed with a special tool without draining the system, but if you are having your system evacuated to measure the amount of refrigerant, I would go ahead and have them changed then for good measure. They are a couple of bucks and a common reason for a/c leaks.

I found the exact ones in my car on the shelf at the local auto parts store. Make sure it's a perfect match because there are several varieties.

https://www.oreillyauto.com/shop/b/air-conditioning-16770/air-conditioning-valves-16795/a-c-schrader-valve-12469/154007952915

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Thanks Digibeam and Stimpy.

Stimpy ,evacuating and recharge to the correct weight with dye was what the tech said they would do.  

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45 minutes ago, yellomurci said:

Thanks Digibeam and Stimpy.

Stimpy ,evacuating and recharge to the correct weight with dye was what the tech said they would do.  

That's good. But make sure they have a machine that can weigh what comes out, otherwise you won't know what's going on with your AC's health.

A lot of shops don't invest in that level of equipment, and you don't want those shops touching your AC. You can go anywhere that has the right equipment to have the refrigerant recovered and recharged on these cars (and any other exotics for that matter) because all exotics use the same AC parts and designs from common cars. You just need to show them where the high and low side are located and the type and weight of refrigerant that is all specified in the manual because those items are unique to the car.

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1 hour ago, yellomurci said:

Freon charge was full so its on to checking fuses and relays tomorrow.

That’s good news.

It’s not hard to access the connector going to the a/c clutch to test for voltage.  It’s on the cross beam.

Our compressors have a traditional clutch, and that’s a possible failure point.

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6 hours ago, yellomurci said:

Freon charge was full so its on to checking fuses and relays tomorrow.

If there is anything I can help you with there, let me know 

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Hi All, 

 

Same issue, however I've done the following, all fuses check out ok, system was low, we removed weighed and filled it to specs. No power going to the compressor, if we pull the plug and give it power it does kick on and blow cold.  Checked the pressure switch at the low pressure side on dryer, it's a 4 wire, jumped yellow to black on both sides still nothing,  

The R14 relay behind the seat doesn't seem to have 12volts on one of the wires going to it, we ran a new wire from this relay to the compressor thinking we have a short going to this,  it kicks on, but doesn't shut off when you shut fans off, only when you turn off ignition so this isn't a solution.

 

Any ideas?

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On 5/7/2019 at 3:27 PM, Kevin M. said:

Hi All, 

 

Same issue, however I've done the following, all fuses check out ok, system was low, we removed weighed and filled it to specs. No power going to the compressor, if we pull the plug and give it power it does kick on and blow cold.  Checked the pressure switch at the low pressure side on dryer, it's a 4 wire, jumped yellow to black on both sides still nothing,  

The R14 relay behind the seat doesn't seem to have 12volts on one of the wires going to it, we ran a new wire from this relay to the compressor thinking we have a short going to this,  it kicks on, but doesn't shut off when you shut fans off, only when you turn off ignition so this isn't a solution.

 

Any ideas?

In terms of things that could fail and cause this problem, one thing to suspect is the AC control panel. It's a self contained unit that is easily replaced, but not inexpensive. You could also have an issue with the temp sensors that feed the control unit causing the control unit not to send the signal. Then there's always wiring issues. I do remember someone having the wire going to the AC compressor in the engine bay get pinched.

Just some things to consider and check.

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Well it turned out to be a fuse after we refilled it or during it must have popped the fuse as it wasn't blow prior, it was the 15 amp fuse behind drivers seat.

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13 hours ago, Kevin M. said:

Well it turned out to be a fuse after we refilled it or during it must have popped the fuse as it wasn't blow prior, it was the 15 amp fuse behind drivers seat.

So the last 3 people (me included) maybe more have needed to change the fuse behind the seat, must be a reason, could it be age related and the compressor clutch is taking more power?

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1 hour ago, yellomurci said:

So the last 3 people (me included) maybe more have needed to change the fuse behind the seat, must be a reason, could it be age related and the compressor clutch is taking more power?

My thoughts exactly.

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The fuses weaken over time from the inrush of operation, they bridge a lot of amperage every time the climate demands which can be every few minutes in some cases.

i would not advise anything higher to try to prevent having to change it out, that will create an issue that isn’t quite as cheap as a fuse and will take way more time to repair

 

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Update, fuse is continuing to pop after driving 1-2 hours, just got back from road trip to Vegas 1k lies and she popped 4 times, Thought it was only while cruising above 100, but one stretch of driving 65 she popped again, now the fun starts trying to find the short.

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7 hours ago, Kevin M. said:

Update, fuse is continuing to pop after driving 1-2 hours, just got back from road trip to Vegas 1k lies and she popped 4 times, Thought it was only while cruising above 100, but one stretch of driving 65 she popped again, now the fun starts trying to find the short.

I'd start by tracing the wire going to the clutch. It's possible that it's been damaged during previous work on the car.

If you can't find a short, it's possible something is wrong with the clutch that is causing it to draw too much power.

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So my AC was working for about 5 miles following changing out the fuse behind the seat then stopped again, am going to look at that fuse but now assume it is something else.

If it is the clutch on the compressor has anyone got a cross over so I dont get the Lambo tax, also any other things to look at, I know the fan for the radiator works as it comes on when the car is idling and gets hot.

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